The “Imsak” Buffer

Q: Am I obliged to stop eating and drinking 15-20 minutes before Fajr?

A: There is no obligation to stop eating 15-20 minutes before Fajr. One may eat and drink until the actual entrance of true dawn.

In fact, it is sunnah to delay suḥūr so long as one does not fear the entrance of Fajr. This is established by the narration of Zayd ibn Thābit, reported in Ṣaḥīḥ al-Bukhārī and Muslim, in which he said that they ate suḥūr with the Prophet ﷺ and then stood for prayer with only the time it takes to recite about fifty verses between them.

If a person fears that continuing to eat may cause them to go past the time of Fajr, then allowing a short buffer is certainly permitted as a precautionary measure, not as an obligation. The cutoff remains certainty of true dawn, not an artificial early time.

Therefore, a person is permitted to keep eating until they are certain that Fajr has entered.

Source: Sharh al-Muntaha & Kashshaf al-Qina